/*
 * Swipe 2.0
 *
 * Brad Birdsall
 * Copyright 2013, MIT License
 *
 */

function Swipe(container, options) {

    "use strict";

    // utilities
    var noop = function() {}; // simple no operation function
    var offloadFn = function(fn) { setTimeout(fn || noop, 0) }; // offload a functions execution

    // check browser capabilities
    var browser = {
        addEventListener: !!window.addEventListener,
        touch: ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch,
        transitions: (function(temp) {
            var props = ['transitionProperty', 'WebkitTransition', 'MozTransition', 'OTransition', 'msTransition'];
            for ( var i in props ) if (temp.style[ props[i] ] !== undefined) return true;
            return false;
        })(document.createElement('swipe'))
    };

    // quit if no root element
    if (!container) return;
    var element = container.children[0];
    var slides, slidePos, width, length;
    options = options || {};
    var index = parseInt(options.startSlide, 10) || 0;
    var speed = options.speed || 300;
    options.continuous = options.continuous !== undefined ? options.continuous : true;

    function setup() {

        // cache slides
        slides = element.children;
        length = slides.length;

        // set continuous to false if only one slide
        if (slides.length < 2) options.continuous = false;

        //special case if two slides
        if (browser.transitions && options.continuous && slides.length < 3) {
            element.appendChild(slides[0].cloneNode(true));
            element.appendChild(element.children[1].cloneNode(true));
            slides = element.children;
        }

        // create an array to store current positions of each slide
        slidePos = new Array(slides.length);

        // determine width of each slide
        width = container.getBoundingClientRect().width || container.offsetWidth;

        element.style.width = (slides.length * width) + 'px';

        // stack elements
        var pos = slides.length;
        while(pos--) {

            var slide = slides[pos];

            slide.style.width = width + 'px';
            slide.setAttribute('data-index', pos);

            if (browser.transitions) {
                slide.style.left = (pos * -width) + 'px';
                move(pos, index > pos ? -width : (index < pos ? width : 0), 0);
            }

        }

        // reposition elements before and after index
        if (options.continuous && browser.transitions) {
            move(circle(index-1), -width, 0);
            move(circle(index+1), width, 0);
        }

        if (!browser.transitions) element.style.left = (index * -width) + 'px';

        container.style.visibility = 'visible';

    }

    function prev() {

        if (options.continuous) slide(index-1);
        else if (index) slide(index-1);

    }

    function next() {

        if (options.continuous) slide(index+1);
        else if (index < slides.length - 1) slide(index+1);

    }

    function circle(index) {

        // a simple positive modulo using slides.length
        //return (slides.length + (index % slides.length)) % slides.length;
        return (length + (index % length)) % length;

    }

    function slide(to, slideSpeed) {

        // do nothing if already on requested slide
        if (index == to) return;

        if (browser.transitions) {

            var direction = Math.abs(index-to) / (index-to); // 1: backward, -1: forward

            // get the actual position of the slide
            if (options.continuous) {
                var natural_direction = direction;
                direction = -slidePos[circle(to)] / width;

                // if going forward but to < index, use to = slides.length + to
                // if going backward but to > index, use to = -slides.length + to
                if (direction !== natural_direction) to =  -direction * slides.length + to;

            }

            var diff = Math.abs(index-to) - 1;

            // move all the slides between index and to in the right direction
            while (diff--) move( circle((to > index ? to : index) - diff - 1), width * direction, 0);

            to = circle(to);

            move(index, width * direction, slideSpeed || speed);
            move(to, 0, slideSpeed || speed);

            if (options.continuous) move(circle(to - direction), -(width * direction), 0); // we need to get the next in place

        } else {     

            to = circle(to);
            animate(index * -width, to * -width, slideSpeed || speed);
            //no fallback for a circular continuous if the browser does not accept transitions
        }

        index = to;
        offloadFn(options.callback && options.callback(index, slides[index]));
    }

    function move(index, dist, speed) {

        translate(index, dist, speed);
        slidePos[index] = dist;

    }

    function translate(index, dist, speed) {

        var slide = slides[index];
        var style = slide && slide.style;

        if (!style) return;

        style.webkitTransitionDuration = 
            style.MozTransitionDuration = 
            style.msTransitionDuration = 
            style.OTransitionDuration = 
            style.transitionDuration = speed + 'ms';

        style.webkitTransform = 'translate(' + dist + 'px,0)' + 'translateZ(0)';
        style.msTransform = 
            style.MozTransform = 
            style.OTransform = 'translateX(' + dist + 'px)';

    }

    function animate(from, to, speed) {

        // if not an animation, just reposition
        if (!speed) {

            element.style.left = to + 'px';
            return;

        }

        var start = +new Date;

        var timer = setInterval(function() {

                var timeElap = +new Date - start;

                if (timeElap > speed) {

                element.style.left = to + 'px';

                if (delay) begin();

                options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

                clearInterval(timer);
                return;

                }

                element.style.left = (( (to - from) * (Math.floor((timeElap / speed) * 100) / 100) ) + from) + 'px';

                }, 4);

    }

    // setup auto slideshow
    var delay = options.auto || 0;
    var interval;

    function begin() {

        interval = setTimeout(next, delay);

    }

    function stop() {

        delay = 0;
        clearTimeout(interval);

    }


    // setup initial vars
    var start = {};
    var delta = {};
    var isScrolling;      

    // setup event capturing
    var events = {

handleEvent: function(event) {

                 switch (event.type) {
                     case 'touchstart': this.start(event); break;
                     case 'touchmove': this.move(event); break;
                     case 'touchend': offloadFn(this.end(event)); break;
                     case 'webkitTransitionEnd':
                     case 'msTransitionEnd':
                     case 'oTransitionEnd':
                     case 'otransitionend':
                     case 'transitionend': offloadFn(this.transitionEnd(event)); break;
                     case 'resize': offloadFn(setup.call()); break;
                 }

                 if (options.stopPropagation) event.stopPropagation();

             },
start: function(event) {

           var touches = event.touches[0];

           // measure start values
           start = {

               // get initial touch coords
x: touches.pageX,
   y: touches.pageY,

   // store time to determine touch duration
   time: +new Date

           };

           // used for testing first move event
           isScrolling = undefined;

           // reset delta and end measurements
           delta = {};

           // attach touchmove and touchend listeners
           element.addEventListener('touchmove', this, false);
           element.addEventListener('touchend', this, false);

       },
move: function(event) {

          // ensure swiping with one touch and not pinching
          if ( event.touches.length > 1 || event.scale && event.scale !== 1) return

              if (options.disableScroll) event.preventDefault();

          var touches = event.touches[0];

          // measure change in x and y
          delta = {
x: touches.pageX - start.x,
   y: touches.pageY - start.y
          }

          // determine if scrolling test has run - one time test
          if ( typeof isScrolling == 'undefined') {
              isScrolling = !!( isScrolling || Math.abs(delta.x) < Math.abs(delta.y) );
          }

          // if user is not trying to scroll vertically
          if (!isScrolling) {

              // prevent native scrolling 
              event.preventDefault();

              // stop slideshow
              stop();

              // increase resistance if first or last slide
              if (options.continuous) { // we don't add resistance at the end

                  translate(circle(index-1), delta.x + slidePos[circle(index-1)], 0);
                  translate(index, delta.x + slidePos[index], 0);
                  translate(circle(index+1), delta.x + slidePos[circle(index+1)], 0);

              } else {

                  delta.x = 
                      delta.x / 
                      ( (!index && delta.x > 0               // if first slide and sliding left
                         || index == slides.length - 1        // or if last slide and sliding right
                         && delta.x < 0                       // and if sliding at all
                        ) ?                      
                        ( Math.abs(delta.x) / width + 1 )      // determine resistance level
                        : 1 );                                 // no resistance if false

                  // translate 1:1
                  translate(index-1, delta.x + slidePos[index-1], 0);
                  translate(index, delta.x + slidePos[index], 0);
                  translate(index+1, delta.x + slidePos[index+1], 0);
              }

          }

      },
end: function(event) {

         // measure duration
         var duration = +new Date - start.time;

         // determine if slide attempt triggers next/prev slide
         var isValidSlide = 
             Number(duration) < 250               // if slide duration is less than 250ms
             && Math.abs(delta.x) > 20            // and if slide amt is greater than 20px
             || Math.abs(delta.x) > width/2;      // or if slide amt is greater than half the width

         // determine if slide attempt is past start and end
         var isPastBounds = 
             !index && delta.x > 0                            // if first slide and slide amt is greater than 0
             || index == slides.length - 1 && delta.x < 0;    // or if last slide and slide amt is less than 0

         if (options.continuous) isPastBounds = false;

         // determine direction of swipe (true:right, false:left)
         var direction = delta.x < 0;

         // if not scrolling vertically
         if (!isScrolling) {

             if (isValidSlide && !isPastBounds) {

                 if (direction) {

                     if (options.continuous) { // we need to get the next in this direction in place

                         move(circle(index-1), -width, 0);
                         move(circle(index+2), width, 0);

                     } else {
                         move(index-1, -width, 0);
                     }

                     move(index, slidePos[index]-width, speed);
                     move(circle(index+1), slidePos[circle(index+1)]-width, speed);
                     index = circle(index+1);  

                 } else {
                     if (options.continuous) { // we need to get the next in this direction in place

                         move(circle(index+1), width, 0);
                         move(circle(index-2), -width, 0);

                     } else {
                         move(index+1, width, 0);
                     }

                     move(index, slidePos[index]+width, speed);
                     move(circle(index-1), slidePos[circle(index-1)]+width, speed);
                     index = circle(index-1);

                 }

                 options.callback && options.callback(index, slides[index]);

             } else {

                 if (options.continuous) {

                     move(circle(index-1), -width, speed);
                     move(index, 0, speed);
                     move(circle(index+1), width, speed);

                 } else {

                     move(index-1, -width, speed);
                     move(index, 0, speed);
                     move(index+1, width, speed);
                 }

             }

         }

         // kill touchmove and touchend event listeners until touchstart called again
         element.removeEventListener('touchmove', events, false)
             element.removeEventListener('touchend', events, false)

     },
transitionEnd: function(event) {

                   if (parseInt(event.target.getAttribute('data-index'), 10) == index) {

                       if (delay) begin();

                       options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

                   }

               }

    }

    // trigger setup
    setup();

    // start auto slideshow if applicable
    if (delay) begin();


    // add event listeners
    if (browser.addEventListener) {

        // set touchstart event on element    
        if (browser.touch) element.addEventListener('touchstart', events, false);

        if (browser.transitions) {
            element.addEventListener('webkitTransitionEnd', events, false);
            element.addEventListener('msTransitionEnd', events, false);
            element.addEventListener('oTransitionEnd', events, false);
            element.addEventListener('otransitionend', events, false);
            element.addEventListener('transitionend', events, false);
        }

        // set resize event on window
        window.addEventListener('resize', events, false);

    } else {

        window.onresize = function () { setup() }; // to play nice with old IE

    }

    // expose the Swipe API
    return {
setup: function() {

           setup();

       },
slide: function(to, speed) {

           // cancel slideshow
           stop();

           slide(to, speed);

       },
prev: function() {

          // cancel slideshow
          stop();

          prev();

      },
next: function() {

          // cancel slideshow
          stop();

          next();

      },
getPos: function() {

            // return current index position
            return index;

        },
getNumSlides: function() {

                  // return total number of slides
                  return length;
              },
kill: function() {

          // cancel slideshow
          stop();

          // reset element
          element.style.width = 'auto';
          element.style.left = 0;

          // reset slides
          var pos = slides.length;
          while(pos--) {

              var slide = slides[pos];
              slide.style.width = '100%';
              slide.style.left = 0;

              if (browser.transitions) translate(pos, 0, 0);

          }

          // removed event listeners
          if (browser.addEventListener) {

              // remove current event listeners
              element.removeEventListener('touchstart', events, false);
              element.removeEventListener('webkitTransitionEnd', events, false);
              element.removeEventListener('msTransitionEnd', events, false);
              element.removeEventListener('oTransitionEnd', events, false);
              element.removeEventListener('otransitionend', events, false);
              element.removeEventListener('transitionend', events, false);
              window.removeEventListener('resize', events, false);

          }
          else {

              window.onresize = null;

          }

      }
    }

}


if ( window.jQuery || window.Zepto ) {
    (function($) {
     $.fn.Swipe = function(params) {
     return this.each(function() {
         $(this).data('Swipe', new Swipe($(this)[0], params));
         });
     }
     })( window.jQuery || window.Zepto )
}

